Updated 5:44 p.m. | State Speaker Chris Donovan's (D) former campaign manager, Joshua Nassi, has been charged in connection with a contribution scandal that has put the Donovan campaign for the 5th district on the skids, according to the Danbury News Times.

Federal authorities have spent the past several months investigating an alleged quid pro quo scheme involving donations to the Donovan campaign and tobacco tax legislation in the state House. Nassi was dismissed from the campaign in early June.

Donovan campaign Finance Director Robert Braddock Jr. was arrested in early June. Others on the tobacco side of the alleged plot were charged today as well. The Hartford Courant has a rundown of those charged so far here.

The race has become a headache for Democrats. Donovan was the presumptive frontrunner and successor to Rep. Christopher Murphy (D), who is vacating the seat to run for Senate. Labor and liberals have steadfastly backed Donovan's run for Congress and that support might well be enough to pull him through the primary.

At least two campaigns so far have weighed in on the matter.

Democratic rival Dan Roberti called Donovan's approach "public-be-damned" and called for him to leave the race.

"Today’s arrests of individuals connected to the corruption case swirling around Chris Donovan’s 5th District Congressional campaign removes all doubt Mr. Donovan should end his bid for the Democratic Party’s nomination," he wrote in a statement.

Businessman Mark Greenberg (R) also called for Donovan to withdraw and issued a recurring criticism of Donovan.

"It is clear that Donovan either knew or should have known that illegal activity was occurring in his campaign," Greenberg wrote in a statement.

Roll Call rates this race as Likely Democratic, but much of that rating is dependent on how the two parties' primaries and this scandal play out.

Updated 5:44 p.m.

In a statement, Donovan said he was not involved.

"I expected that sooner or later that there would be developments in this ongoing investigation. What I didn’t expect, what I’m practically speechless about, is that in spite of my hard-earned reputation for honesty and my career working for campaign finance reform, that there are people who thought they could buy my vote. That’s everything that’s wrong with politics and everything that I've spent my life fighting against," he said.

"My vote is not for sale and it never has been. I’ve already told you and I didn’t know that some of the contributions that came to this campaign were illegal."